2-D Room Mapper Experimental Results


In hindsight, we realized that we did not do the type of testing associated
with measuring devices.  We accomplished using ultrasonic waves to measure
distances by displaying a proportional readout on to a VGA screen, but due to
oversight we failed to figure out exactly how accurate the 2-D Room Mapper was.

We also realize that our testing procedure was far from scientific due to time
resraints and more oversight.(We were just happy the system performed in the
manner that was expected)

Are none so scientific test procedures was as follows. We paced out from a 
wall - one, two, and three steps and took measurements from each point.
We foolished assumed that one pace equalled roughly one meter.  At one pace
from the wall, the 2-D Mapper displayed a distance of roughly a meter on the
VGA screen.  This was in the form of a line one third the distance of our
reference line, which is also displayed on to the screen.  The two paces out,
the 2-D Mapper displayed a distance of roughly 2 meters on the VGA screen. 
This was in the form of a tine two thirds the distance of our reference line. 
At three meters out, the 2-D Mapper displayed a line the same length as the
reference line signifying 3 meters.

The system was also designed to display a maximum of 3 meters even if it has
measured a further distance.  This was due to our decision on the number of
bits our pulse counter was.

Further tests was also done to convince ourselves of proper operation.  These
tests began at one, two, and three paces out from the Mapper.  We had placed an
object(metal grounding plate) roughly half the distance between the Mapper and
and our "percieved" one meter point.  The 2-D Mapper displayed this measurement
as roughly one sixth of the reference thus indicating roughly a meter.  We then
further proceed to move the object towards and away from the 2-D Mapper in
roughly centimeter increments and took more readings.  As the object was placed
closer and closer to the the 2-D Room Mapper, the short displayed became
shorter and shorter.  With the object roughly 1 cm away from the 2-D Mappers
sensors, the monitor displayed a measurement line of roughly one to three
pixels widths in length.  At the object's distance was incremented (at roughly
centimeter increments), the 2-D Mapper indicated the increases by increasing
the measurement line.  All measurements indicated were proportional to the
actual distance between the Mapper and the object.  Moving the object 5cm would
make the reading change more than if you were to move the object 1cm. 
Incremental measurements were tested at points roughly one, two, and three
meters away from the Mapper.  All tests produced the expected result from our
calucations, which indicated to us proper operation of the system.

Lastly we semi-tested the Mapper's ability to take readings of objects that
were at angle to its sensor array.  Due to time consraints, this too was not
test extensively.  We found that at angles of roughly 30 to 40 degrees, the
mapper had trouble with accurate readings.  We figure this to be from the
ultrasonic wave reflecting off the object.

In conclusion, during the testing of the 2-D Room Mapper the accuracy of its
measurements were the least of ours concerns.  Our goal was to produce a 
functioning system first, and a accurate system second. This was due to a lack 
of time, not due to us not caring about it.  It was something we assumed we were
going to do at the start of our design(measurement of accuarcy), and all
designed components were designed with accuracy in mind by due to time
constrants it slipped our minds.